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  <title>Get an extended attribute</title>
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  <div id="layout-content"><div id="function.xattr-get" class="refentry">
 <div class="refnamediv">
  <h1 class="refname">xattr_get</h1>
  <p class="verinfo">(PECL xattr &gt;= 0.9.0)</p><p class="refpurpose"><span class="refname">xattr_get</span> &mdash; <span class="dc-title">
   Get an extended attribute
  </span></p>

 </div>
 <div class="refsect1 description" id="refsect1-function.xattr-get-description">
  <h3 class="title">说明</h3>
  <div class="methodsynopsis dc-description">
   <span class="methodname"><strong>xattr_get</strong></span>
    ( <span class="methodparam"><span class="type">string</span> <code class="parameter">$filename</code></span>
   , <span class="methodparam"><span class="type">string</span> <code class="parameter">$name</code></span>
   [, <span class="methodparam"><span class="type">int</span> <code class="parameter">$flags</code><span class="initializer"> = 0</span></span>
  ] ) : <span class="type">string</span></div>

  <p class="para rdfs-comment">
   This function gets the value of an extended attribute of a file.
  </p>
  <p class="para">扩展的属性有两种 不同的命名空间：user
和 root。user 命名空间对所有用户均有效，而 root
命名空间仅对拥有 root 权限的用户有效。
xattr 默认在 user 命名空间上操作，但可使用
<code class="parameter">flags</code> 参数进行更改。</p>
 </div>

 <div class="refsect1 parameters" id="refsect1-function.xattr-get-parameters">
  <h3 class="title">参数</h3>
  <p class="para">
   <dl>

    
     <dt>
<code class="parameter">filename</code></dt>

     <dd>

      <p class="para">
       The file from which we get the attribute.
      </p>
     </dd>

    
    
     <dt>
<code class="parameter">name</code></dt>

     <dd>

      <p class="para">
       The name of the attribute.
      </p>
     </dd>

    
    
     <dt>
<code class="parameter">flags</code></dt>

     <dd>

      <p class="para">
       <table class="doctable table">
        <caption><strong>Supported xattr flags</strong></caption>
        
         <tbody class="tbody">
          <tr>
           <td><strong><code>XATTR_DONTFOLLOW</code></strong></td>
           <td>Do not follow the symbolic link but operate on symbolic link itself.</td>
          </tr>

          <tr>
           <td><strong><code>XATTR_ROOT</code></strong></td>
           <td>Set attribute in root (trusted) namespace. Requires root privileges.</td>
          </tr>

         </tbody>
        
       </table>

      </p>
     </dd>

    
   </dl>

  </p>
 </div>

 <div class="refsect1 returnvalues" id="refsect1-function.xattr-get-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   Returns a string containing the value or <strong><code>FALSE</code></strong> if the attribute doesn&#039;t 
   exist. 
  </p>
 </div>

 <div class="refsect1 examples" id="refsect1-function.xattr-get-examples">
  <h3 class="title">范例</h3>
  <p class="para">
   <div class="example" id="example-2857">
    <p><strong>Example #1 Checks if system administrator has signed the file</strong></p>
    <div class="example-contents">
<div class="phpcode"><pre><span style="color: #000000">
<span style="color: #0000BB">&lt;?php<br />$file&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #DD0000">'/usr/local/sbin/some_binary'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$signature&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">xattr_get</span><span style="color: #007700">(</span><span style="color: #0000BB">$file</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'Root&nbsp;signature'</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">XATTR_ROOT</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">/*&nbsp;...&nbsp;check&nbsp;if&nbsp;$signature&nbsp;is&nbsp;valid&nbsp;...&nbsp;*/<br /><br /></span><span style="color: #0000BB">?&gt;</span>
</span>
</pre></div>
    </div>

   </div>
  </p>
 </div>

 <div class="refsect1 seealso" id="refsect1-function.xattr-get-seealso">
  <h3 class="title">参见</h3>
  <p class="para">
   <ul class="simplelist">
    <li class="member"><span class="function"><a href="xattr_list.html" class="function" rel="rdfs-seeAlso">xattr_list()</a> - Get a list of extended attributes</span></li>
    <li class="member"><span class="function"><a href="xattr_set.html" class="function" rel="rdfs-seeAlso">xattr_set()</a> - Set an extended attribute</span></li>
    <li class="member"><span class="function"><a href="xattr_remove.html" class="function" rel="rdfs-seeAlso">xattr_remove()</a> - Remove an extended attribute</span></li>
   </ul>
  </p>
 </div>

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